Microscopic oil uptake mechanisms in fried products
Abstract
The increasingly poor perception of fried products encourages the development of rupture technologies to reduce oil uptake. The current available descriptions of oil uptake mechanisms remain incomplete, neglecting: (i) the critical role of the total pressure gradient inside hygroscopic materials during cooling, (ii) the coupling between mechanical ruptures and oil uptake routes, (iii) the different configurations of biphasic oil-air flow inside the material: co- and counter-currents. This paper demonstrates how additional understanding could be gained by using high-resolution, dynamic and non-invasive techniques, including X-ray micro-computed tomography, UV-VIS laser or synchrotron source microscopy, and new generations 3D percolation models fitted on digitized structures. The critical role of air in hindering/preventing oil absorption is particularly highlighted. The effects of cell injuries and starch on the creation of cavities and oil absorption are discussed on parfried French fries subjected to different surface pretreatments.